Robots are utilized in a variety of manufacturing environments. For example, a robot may be placed within a cell (i.e., a predefined volume of space) on an assembly line. The robot may perform work upon an incoming part placed in the cell before the part is moved onward to a next cell to receive further processing. For example, a robot may perform work by operating an end effector in order to drill holes into the part, apply rivets to the part, etc.
While robots operate effectively and efficiently in manufacturing environments, a robot has a risk of unintentional collision with an object within the cell during normal operation. For example, computer models may suggest the robot will occupy certain predefined locations within the cell. However, if the robot and/or the part being worked on are not installed in the cell exactly at their expected positions and/or orientations, a collision may occur. Furthermore, a robot may be covered in dressing, which includes hydraulic hoses, power cabling, etc., and this dressing may not be sufficiently accounted for in the computer model for the cell. Thus, the dressing may unintentionally collide, snag, or catch on other objects within the cell.
To address these issues, it is not uncommon for a technician using a form of Coordinate Measurement Machine (CMM) to measure the position and/or orientation of various components within the cell, including the robot, the part, etc. However, these objects are measured in the coordinate system of the CMM, and the measurements of these objects include residual errors. Thus, in order to determine the distance between any point of an end effector of the robot and a part, it may be necessary to convert these measurements (which include errors) from the CMM coordinate system to the coordinate system for the robot. Thus, depending on the magnitude of the CMM measurement errors, collisions may still occur. Also, these measurements require dedicated equipment and time to process and periodically certify.